ONE RIFLE. EVERY CALIBER.
The MBZ-15 Multi Cal. One serialized lower, one patented upper, and every barrel you'll ever want.
Watch the barrel swap, start to finish.
The receiver is the system.
Every quick-change AR on the market does the same thing: it bolts a mechanism onto a standard upper. Levers. Cam locks. Coupling plates. Takedown pins. Parts that add weight, add cost, and add ways to fail.
MBZ didn't add anything. We cut the threads into the receiver itself.
The barrel threads straight into the upper and locks with its own nut. The handguard threads on over it. Two threads, one nut, zero levers. Nothing to break, nothing to lose, nothing to adjust.
Others claim it. We built it.
Built on a patented upper receiver design. Nobody else makes it.
Four moves. Done.
- Handguard off.
- Barrel out.
- New barrel in. Snug the nut with the supplied wrench.
- Handguard on.
Under a minute once it's in your hands. No vise. No torque wrench. No gunsmith. Your kitchen table is the armory.
Charge from the side.
The MBZ-15 runs a side-charging bolt carrier. The handle rides on the carrier and comes out the right side of the upper.
Chamber a round, lock the bolt, clear a stoppage, all without leaving the gun. No reaching under a scope. No breaking your cheek weld. Run a full-size LPVO or a suppressor and the charging handle is right where your support hand already is.
Same rifle. Same optic. Six calibers.
Bolt family A. Barrel only.
5.56 NATO · .223 Wylde · .300 Blackout · .350 Legend
Bolt family B. Barrel plus bolt assembly.
6mm ARC · 6.5 Grendel
Pull the bolt carrier group, swap the bolt assembly, seat the barrel. That's the whole change between families.
Some calibers run on their own magazine. Every barrel kit page tells you exactly what you need before you order: barrel, bolt assembly, magazine. No surprises at the range.
Three ways in.
Rifle Bundles. The complete MBZ-15 Multi Cal with barrels, bolt assemblies and wrench, boxed and ready. Ships to your FFL.
Upper Kits. Turn your AR-15 into a multi-caliber rifle. The MBZ upper drops onto any mil-spec lower you already own. Add barrel kits as you go. Ships to your door. No FFL required.
Barrel Nuts. Already have a barrel you love? Our nut, your barrel, our upper. Put a good trigger, a good barrel and good optics on it and go shoot.
Straight talk.
The handguard rotates to thread on. That leaves no room for M-LOK backing nuts inside it, so through-mounted M-LOK hardware is out for now. Clamp-on lights, lasers and grips work as they always have.
That's the trade for a one-minute caliber change. We made it on purpose, and we'd rather tell you now than have you find out at the bench.
Built in Wisconsin. Backed by people who shoot it.
The MBZ-15 comes out of Evansville, Wisconsin, from a small shop that builds every rifle it sells. Call us. A person who has run this gun will pick up.
+1 (608) 574-0139